The proposed research seeks to learn more about hemostatic and fibrinolytic mechanisms through three approaches: 1) Observations on patients with congenital hemorrhagic diseases; 2) Study of acquired hemorrhagic diseases with special reference to clot-inhibitors and leukofibrinolysis; 3) Study of the phylogenetic development of coagulation mechanisms. The latter involves studies of the blood of many animals from different vertebrate classes. Special studies of chickens will attempt to define their hemostatic mechanism. The proposed research also seeks to determine if therapeutic use of pooled plasma fractions (factors VIII and IX) causes or relates to chronic liver disease in hemophilia. Methods used here will include liver function tests and liver biopsies.